1. Field of the Invention
This invention relates to a start control apparatus of an internal combustion engine particularly in stopping and restarting of cranking at the starting time in a control apparatus of an internal combustion engine for performing cylinder determination and cylinder control based on a crank angle signal of a crankshaft and a cam signal of a cam shaft of an internal combustion engine installed in a vehicle, for example.
2. Description of the Related Art
Generally, in an internal combustion engine of a vehicle engine, etc., a fuel control apparatus is known which is provided with sensors for detecting a crank angle signal and a cam signal of an internal combustion engine to optimally control fuel injection and ignition timings, etc., for a plurality of cylinders in response to drive conditions, and capable of performing cylinder determination and fuel injection and ignition timing control as disclosed in JP-A-11-311146.
However, in cranking at the engine start time, smooth rotation is rare and the rotation speed largely fluctuates. Fuel ignition control is just started and the rotation speed is low in the vicinity of a top dead point or a bottom dead point and becomes high in the vicinity of an intermediate point between the top and bottom dead points. The case where the driver turns off a starter by mistake although the starter is driven and the engine starts to rotate seldom occurs. Further, the case occurs where reliable combustion cannot be conducted at low-temperatures and complete explosion is not reached although the starter is driven for a while and the engine is stopped as the starter is turned off. In some apparatuses in related arts, drive control of an internal combustion engine is continued regardless of the starter being off.
Thus, in the worst case, if rise to a compression top dead point (TDC) cannot be accomplished as the starter is turned off during the compression stroke of a piston, the piston falls just before the TDC and the engine rotates reversely. At this time, rotation stops momentarily because of reverse rotation from forward rotation. Thus, as rotation fluctuates, the input period of a crank angle signal is prolonged and the period of the crank angle signal becomes unequal interval (pitch) and therefore erroneous detection of determining a crank angle lost tooth occurs easily.
As described above, in the apparatus in the related art, in cranking at the starting time, in various starting environments or if the starter is repeatedly turned on and off, there is a possibility that unequal pitch (interval) of the crank angle may be detected erroneously. Consequently, cylinder determination is erroneously made and fuel injection and ignition timing control differs from desired control and there is a fear of incurring backfire, engine lock, etc.